1. Field of the Invention
The present invention generally relates to a highway crash barrier structure for use in a highway barrier system capable of addressing current requirements for improving the crash performance of precast concrete barriers. The barrier system in which the crash barrier structure is used comprises a plurality of rigid sections disposed end-to-end in interlocking relationship with one another. The end of each section has a cavity and is provided with embedded interlocks that join with one another to hold the sections together. Individual sections can be removed or replaced without disrupting the remainder of the barrier system while maintaining proper alignment. The crash barrier structure of the present invention is provided with bolt down pockets which are reinforced with minimal steel yet meet MASH test requirements.
2. Background Description
In recent years, for controlling the flow of traffic, various barrier systems consisting of large sections of precast concrete have been used along highways. The sections can be hoisted into place and removed with greater speed and ease than is usually required to construct more permanent structures. Systems of this type can be dislodged when sufficient external force is applied, resulting in a potential traffic hazard. In some instances, the concrete sections are bolted together to maintain their alignment and assure that they will not be either knocked over or displaced by a colliding vehicle. However, such systems have the disadvantage of being complex and expensive and require considerable time and effort to assemble as well as to remove without disassembling the entire structure when used in road repairs.
Improvements in the system of bolted connections has been the use of looped steel bars that allow for a straight steel pin connection holding the adjoining loops together. This system is expensive and relies on maintaining the pins which also requires one's hands in a dangerous position between the barrier sections during placement or replacement. Vehicle impact on these systems usually requires significant time and expense to remove the pins.
U.S. Pat. No. 5,149,224 to Smith, which is herein incorporated by reference, shows an interlocking highway structure which employs a pair of “J” shaped hooks that connect separate concrete barrier members together without requiring extra hardware. In practice, the end of one precast concrete member is simply slid downward from the top such that the two adjoining precast concrete members have interlocking J connections. The product is commercially marketed as “JJ Hooks®”. The “JJ Hooks®” product includes a short, approximately 12 inches in length, member to which rebar members are welded and extend inward into the precast concrete. While FIG. 3 of U.S. Pat. No. 5,149,224 shows the rebar extending only part way into the precast concrete, in practice the rebar can extend end-to-end with weldment of the rebar to both attachment hooks or can extend only part way into the precast concrete based on “pull out” strength/resistance.
U.S. Pat. No. 7,607,645 to Smith, which is herein incorporated by reference, addresses newer crash test criteria and to allow for greater use of the concrete barriers. These crash criteria are defined by the American Association of Highway & Traffic Officials (AASHTO's) Manual for Assessing Safety Hardware (MASH). The system disclosed in U.S. Pat. No. 7,607,645 is an interlocking barrier system that includes a plurality of rigid upright sections that can be joined together end-to-end using a “J” shaped connection member. The connection member preferably is embedded in a recessed cavity in each end of each section and has an outwardly projected hook. The connection member, as well as its associated hook and an outwardly projected receptacle flange, ran linearly along a line extending from the top to the bottom of each end of each section (e.g., 18″) a distance which almost equals the height of each section. A plurality of bars (e.g., rebar) are welded or otherwise joined to the connection member and extend into the concrete section a distance that the minimum “pull out” strength resistance is met. In one embodiment, the rebar may extend end-to-end in the barrier structure. In another embodiment, the rebar do not traverse end-to-end distance of the section, and may extend two feet or more. This configuration eliminates or reduces the rotational forces imparted by a collision at one end of the section being imparted at the other end, thus making the interlocking structure more compliant with newer crash test safety requirements.